You mention rm -rf * in the wrong directory, I have witnessed this first hand as a colleague of mine many years ago was editing the zone files on our DNS server. Being one of the few *nix heads in the company he liked to highlight his prowess by ssh'ing into the remote servers and changing things live, skipping the FTP process that everyone else needed to use.
Anyway, one day we were all sitting around doing our work and we hear a GASP from his desk. We look over and he has his head in his hands staring at his screen with his mouth agape, and we ask him what's wrong. It takes him a minute or two to regain his composure and explain to us that instead of typing vi * he'd typed rm * and indiscriminately deleted all of the zone files for not only our own projects but those of our hosted customers. He then spent the next couple of hours reconstructing everything from DNS queries and his terminal scrollback.
Fun times!